Vacuum power clutch



June. 25, 1940.

H. J. vDE N. M COLLUM Er AL VACUUM POWER CLUTCH a Sheets Sheet 1Original Filed Dec. 20, 1930 INVENTORS J DeN Henry McCoI/um BY James K.McCoZlum ATTORNEY June 1940- H. J. DE N. MccoLLpM ET AL Re- 21,491

VACUUM POWER CLUTCH Original Filed Dec. 20, 1930 3 Shasta-Sheet 2 r 2546 I 24 3e 5 4a 8 20a 2e 23 Y 42 Z0 I2 $3 V r w 50a I Ic 7 52 20a 22 22a 40 I4 Z8 4 22 23 a? T- j- INVENTORS Henry J De/V. McCoHum BY James H.K. McCol/um ATTORNEY J1me 1940- H. J. DE N. MccoLLuM ET m. 21,491

VACUUM POWER CLUTCH Original Filed Dec. 2O, 1930 3 s t s t 3 INVENTORSHenry J De/V. 'McCollum by James H. h. McCo/lum ATTORN %Y Reissued June25, 1940 UNITED STATES PATENT OFFICE VACUUM POWER CLUTCH Original No.1,858,999, dated May 17, 1932, Serial No. 503,767, December 20, 1930.Application for reissue August 4, 1933, Serial No.

27 Claims.

Our invention relates generallyv to improvements in power operatedclutches for motor cars and the objects of our improvements are, first,to provide a mechanism which automatical- 5 1y engages and disengagesthe clutch, second, to provide a mechanism which automatically causesthe automobile, or motor vehicle to coast. or freewheel whenever thefoot pressure is completely removed from the accelerator by thendisengaging, or opening, the clutch, but which will cause the clutch toengage, or close, during the initial movement of the accelerator pedalproduced by the usual foot pressure, and before the carburetor throttleis opened from idling position. Conversely, while the foot pressure isbeing gradually removed from the accelerator pedal the clutch willremain in engagement after the throttle has been closed to idlingposition and so continue until said pedal has practically reached thelimit of its upward or backward movement.

More specifically the present invention sup-- plies a means for moreaccurately graduating and controlling the action of the automaticmechanism when closing the clutch, such nicely grad uated control beingnecessary to prevent jerks in the movements of the vehicle and shocks tothe mechanism, which might result from a too rapid and sudden completeengagement between the members of the usual friction clutch used in Inc-10 tor cars to which our invention may be applied.

We attain these objects by the mechanism illustrated in the accompanyingthree sheets of drawings in which like numbers represent the same partsin the various figures.

Fig. l is a diagrammatic view, with parts broken away, and others shownin section, of one form of apparatus embodying the invention as attachedto the power transmission clutch pedal, carburetor throttle and intakemanifold U of a motor car, a single acting cylinder and piston beingshown.

Fig. 2 is an enlarged, sectional view of the same form of fluid.pressure controlling valve, with a ball and socket operating connectionthere- Fig. 3 is a detail cross section on line 3 3 of Fig. 1.

Fig. 4 is a detail, side view of the parts shown in Fig. 3.

i Fig. 5 is a detail sectional View on anenlargcci scale of the twincut-out valves indicated in l.

Fig. 6 is a view similar to Fig. 1 showing a modification in which theclutch operating cylinder and piston are double-acting.

5 Fig. '7 is a detail side view of a modified form of single cut-outvalve adapted for installation on the instrument board of the motor car,and Fig. 12 is a diagram showing its connections to other parts of theapparatus.

Fig. 8 is a detail section on line 8-8 of Fig. 9, and Fig. 9 is asection on line 99 of Fig. 8, showing a butterfly valve which may besubstituted for the plug valve shown in Figs. 1 and 2.

Figs. 10 and 11 are similar views of such a valve for use in connectionwith the double acting cylinder and piston of Fig. 6.

Throughout the drawings like reference characters indicate like parts.

Fig. 1 illustrates one embodiment of our invention in which I is avacuum cylinder having I having a cup-leather packing which prevents airpassing around it into the cylinder space behind it, but allows air topass out slowly around it, and 3 is a piston rod extending throughcylinder head Ia but not having an air-tight bearing therein. The outerend of said piston rod is pivotally connected to the clutch lever 4mounted on rotatable shaft to and normally pulled toward clutchengaging, or closing, position by a spring such as 5 in the usual way. 6represents generally the intake-manifold of an internal combustion motorto which the carburetor mixture tube 9 is connected, Ill being thecarburetor throttle valve controlled by lever la and spring I 017, whichlatter normally holds one extremity of the valve arms I la against fixedstop I I, with the valve in adjusted position for idling the motor.

The carburetor throttle is controlled. in the usual manner by alost-motion apparatus composed of the two-part connecting rod, sectionsI8 and I9 of which are kept in line by tubular clip I6 fast on sectionI9. Compression spring I! is confined between clip I6 and a similar oneI5 which is fast on rod section I8. The enlarged ends of these clips aresplit as shown in Figs. 3 and 4, so that each can be clamped down on thesupporting rod section by set screws Ifia. The other end of thisconnecting rod is pivoted at 280, to swinging link Illa mounted on afixed pivot I91), and also to the accelerator plunger I2 which passesthrough the foot board I3. A tension spring I4 normally holds theaccelerator plunger or pedal in retracted position, as shown in Fig. 1,with a gap between the adjacent ends of the rod sections I8, I9, whichgap determines the amplitude of the lost motion.

The closed end of the cylinder is connected by conduit 36 to a portcasing 23 which surrounds the casing 1 of the fluid pressure controllingvalve and communicates with a plurality of ports 22 in said casing. 31is a conduit connecting the intake manifold 6 with said valve casing 1at another point through port 4|. The piston valve 8 has a medialportion 26 of reduced diameter which is long enough to brid e ports 22and 4| when the accelerator pedal I2 is retracted and remains in theposition shown in Fig. l. Conduit 36 is controlled by the three-wayvalve 24 which may open passage 2411 through the conduit when inposition shown in Fig. 5, or vent the interior of cylinder to theatmosphere through valve passages 24a, 241), when said valve is rotatedin a clockwise direction. Similarly conduit 31 is controlled by athree-way valve 25 which affords passage therethrough by channel 25awhen the a parts are in the position shown in Fig. 5, or closes off theconnection to the intake manifold and vents the valve casing 1 to theatmosphere when said valve is rotated 90 in a clockwise direction. Thetwo valves are connected so as to be operated in unison by push-rod 25cpivoted to the levers of both valves and extending through the footboard I3 so that it may be manipulated by the operator.

The piston valve 8 has cylindrical enlargements 2|, 2|, at or neareither end, while its right hand extremity tapers slightly, as indicatedat 20. It is connected by wrist pin 21 to link 28, the other end ofwhich is connected to pivot 280 which unites it and the acceleratorplunger, pedal or rod l2 and the carburetor rod section Ill.

The operation of the mechanism shown and hereinbefore described is asfollows:

With the foot pressure off the accelerator |2 the spring l4 holds theparts in position, as shown in Fig. 1, which is the idling position ofthe carburetor and, the manifold 6 being connected by means of pipe 31,ports 4| and 22, the annular space around the valve portion 26 ofreduced diameter, and the pipe 36 to the vacuum cylinder l, the piston2, rod 3 and clutch pedal 4 will be pulled to the left and all partsheld in the clutch-disengaged position so that, with the valve 8 asshown in Fig. 1, the motor vehicle will free-wheel or coast.

To start from a stand-still in low gear a comparatively slow clutchengagement is required while the motor is turning at a moderate speed,for smooth starting, and this is obtained by the tapered portion 20 ofvalve 8, as this taper graduates the amount of air that can pass, in agiven time, from the atmosphere into the cylinder I when the acceleratorplunger or pedal I2 is pressed down or to the left to a given degree bythe foot. The farther the pedal I2 is pressed by the foot the faster theengagement of the clutch will be and the faster the motor will be turninwhen the clutch engages. When changing from first to second, and from.second to high, gear, a rapid clutch engagement is necessary for quickacceleration, and to obtain this rapid clutch engagement the footaccelerator I2 is pressed far enough so that the right hand end of thevalve 8 will pass the left hand edge of the ports 22 thus giving themaximum opening between the atmosphere and the cylinder I while themotor is revolving at a desirably higher speed. The portions 2| of thevalve 8 are of full cylindrical cross section to fit closely in valvecasing 1 so as to prevent leakage between the annular space around thevalve portion 26 and the atmosphere.

ing of said throttle valve.

In other words the piston valve has the proper amount of lap in relationto the ports 22 and 4|. Lost motion is allowed between the parts I8 andIQ of the carburetor throttle rod so that the clutch can be engagedwhile the carburetor throttle is in the idling position and while themotor is idling. As a result of the hereinbefore described constructionthe gap .between the adjacent ends of throttle rod sections I8 and I9 isopen while the operators foot is off the accelerator pedal I2, and theintake-manifold is then connected to cylinder I so that clutch pedal 4is automatically held in depressed position, causing the powertransmission clutch to be held in disengaged position and the carburetorthrottle in idling adjustment.

The first movement of accelerator pedal |2 to the left closes ports 22,thus shutting off the suction from the intake manifold 6, andthereafter, as the tapered portion 2!] of the valve comes opposite ports22, it begins to admit air through them from air ports 5|! in the righthand end of valve casing 1, and through said ports 22, to the interiorof cylinder I, thus permitting the spring 5 to begin closing the clutch.Further movement I of the accelerator rod l2 to the left admits more airto complete the clutch closure and also closes the gap between sectionsI8 and H! of the throttle rod and begins to open the carburetor throttlevalve l0, so that as the clutch is then completely engaged, thereafterthe car may be driven by the motor at any speed determined by furtheropen- When the accelerator rod or pedal I2 is allowed to be pulled backby the spring l4, the carbuertor throttle valve is first brought back toidling position and then the final movement of the accelerator pedal tothe right closes the connection between ports 22 and the atmosphere andthereafter opens the connection from cylinder I through the valve casing1 to conduit 31, and the suction of the intake manifold then operates onpiston 2 to pull the clutch out of engagement. As a result the clutchmay be let into engagement before the carburetor throttle begins toopen, and, conversely, the clutch can only be pulled out of engagementafter the carburetor throttle has been closed.

4a is the clutch-operating shaft to which clutch pedal 4 is keyed. 48indicates stops fastened in the left-hand end of valve casing 1 to limitthe movement of valve 8 in that direction. 49 is an inturned, annularlip at the right-hand end of said valve casing to limit movement of thevalve in the other direction. This latter also serves as a stop for theaccelerator plunger or pedal l2. A short section of rubber hose 46 isheld at one end to conduit 36 by a band clip, as indicated, and at theother end is similarly held to the nipple 41 set in the wall of cylinderIn Fig. 2 a ball and socket connection 40 between valve 8 and itsconnecting rod 28 takes the place of wrist pin 21 in Fig. 1. Figs. 8 and9 show a form of butterfly valve designed as an alternative constructionfor the piston valve shown in Fig. 2. This valve comprises thecylindrical cup-shaped casing 29 in which the butterfly valve 30 ismounted on rotary shaft 35 and held in position by casing head 29a. Thevalve is oscillated by valve lever 34, the motion of which is limited bystop 33. A port 3| in said casing is adapted to be connected by nipple35a with conduit 36 of Fig. 1, and 31a is a similar nipple by which thevalve casing interior may be connected with suction conduit 31. An airport in said casing is shown at 50. The lower wing of the butterflyvalve, which cooperates with port 3|, is backed off at the rear edge ofits operating face, as indicated at 32, this corresponding to thetapered portion 20 of valve 8. The valve lever 34 being connected to theaccelerator pedal through link 28 in the same manner as valve 8 in Fig.1 is connected, this valve will operate in the same way as the pistonvalve 8 to open connection between conduits 36 and 31 and apply suctionto the interior of cylinder I, or, when the butterfly valve is rotatedin a counterclockwise direction (looking at Fig. 9), it will first close3I, shutting off the suction, and then gradually connect cylinder I withair-port 50, as the posite port 3 I.

When a more rapid first stage of clutch closing movement is desired thevacuum cylinder can be made double acting as shown in Fig. 6, the taper20, in this case, being used on the piston heads at both ends of thevalve 8. In the position shown in Fig. 6 the intake manifold 6 isconnected to the cylinder I at the left-hand end of the cylinder I andthe right-hand end or the cylinder I is connected to the atmosphere.When the accelerator I2 is pressed forward by the foot the left-hand endof the cylinder I is connected to the atmosphere and the right-hand endof the cylinder I is connected to the mam-- fold 6 gradually or suddenlyto give a slow or fast clutch enngagement. In other words, the ports areeither opened gradually or suddenly to their full area. In Fig. 6 theparts are shown in the positions occupied just after the accel- |5erator I2 has been released from pressure of the operators foot, andvalve 8 has been thereby pulled quickly to the right, but before anyvacuum so created in the lefthand end of cylinder I, or any inflow ofair to the righthand end 5 thereof has had time to cause piston 2a tomove to the left and open the clutch.

When the space at the right-hand end of cylinnder I, which will befilled with air during such subsequent movement, is still laterconnected 5 with the intake manifold by a movement of the accelerator tothe left under pressure of the operators foot, the pull of spring 5, orof other clutch operating springs, swinging lever 4 in a clutch closingdirection, causes the piston 2a to travel to the right in said cylinderI and such piston movement tends to expel any air in that end thereofthrough conduit 5!, 31, and valve means I, 8, into the manifold. Thisflow is controlled by the adjustment of valve 8 which 5 thereby modifiesto a greater or less extent the speed of clutch closure according to thedegree of such valve opening. The three-way valves 24 and 25 are used toconnect both ends of the cylinder I with the atmosphere and to connect 0the left-hand end of the cylinder I with the port casing 23 and theright-hand end of the cylinder I with the left-hand port casing 52 ofthe valve casing I. In this form the piston La has a double cup-leatherpacking and the cylinder 5 head II) has a flexible lip packing Ic turnedbacked-off portion 32 of the valve comes 011- form of valve issubstituted in Fig. 6, conduit 5I will be connected to nipple 5Ia, whichtakes the place of valve casing 52 in Fig. 6 and opens into the valveport 53 with which the upper wing of the butterfly valve (Fig. 11)cooperates, said valve face having a backed-off portion 32a. When theparts are in the position shown in Fig. 11, the suction through conduit31 is shut ofi from both ends of the cylinder I. If the valve 38 isrotated in a clockwise direction until its operating lever 34 comes upagainst stop 33, the conduit 36, which is connected to nipple 36a, willbe subjected to suction through the opened valve port 3| and the otherend of the cylinder will be vented to the atmosphere, as port 53 isopened by the upper valve Wing and thrown in connection with air port50. If, on the other hand, the valve 3% is rotated in a counterclockwisedirection, the right-hand end of the cylinder I is gradually subjectedto suction as port 53 is opened and thrown in connection with conduit31. At the same time the other end of the cylinder is vented to theatmosphere through ports 3I and 50.

Fig. 6 also shows another means for ensuring the proper amount of lag inthe opening of the carburetor throttle after the valve 8 has sodistributed the fluid pressure as to close, or permit the engagement ofthe clutch. In the arrangement there shown the outer end of throttle rodI8 is pivoted at IBb to the free end of link IIia which swings aboutfixed pivot IBc in the same plane in which the adjustable tappet I9.r,carried by link I9a, swings. When the accelerator pedal I2 isfree andthe parts are in the position shown in Fig. 6, the gap between Him andI6a corresponds to that between the ends of throttle rod sections I8 andI9 in Fig. 1. Not until after the accelerator pedal and valve 8 havebeen pushed far enough to the left to close off the suction from theleft side of piston 2a and apply it to the right side thereof to beginto close the clutch, will I9a: strike I60, and then begin to open thethrottle.

The cut-out valves 24 and 25 in Fig. 6 are not connected together.Consequently either can be slightly turned, if desired, to partlythrottle the suction on the corresponding end of cylinder I, and so slowdown the rate of piston motion there by created. When both 24 and 25 areturned through 90 the suction is wholly cut off and both ends ofcylinder I (in Fig. 6) are vented to the atmosphere.

The same result is accomplished by the one double cut-out valve shown inFig. 7, where 54 is a plug valve having two through-passages, 24a and25a, registering respectively with conduits 36 and 37 (in the samemanner as shown in Fig. 5). The valve casing 55 and cover 56 are held byscrews to the instrument board 38, through a hole in which the knurledhead 39 of the valve spindle projects. 51 is an air port in this valvecasing with which one end of valve passage 24a will register when thevalve is rotated 9G (also as shown in Fig. 5). The conduits and 31.which are formed of flexible copper tubing, are then made long enough toloop up to the valve casing 55 on the instrument board as illustrated inFig. 12, and consequently this one valve does the work of the twoconnected valves 24 and 25 shown in Figs. 1 and 5. That is to say, itkeeps open the connections from manifold B to valve port 4| and fromport casing 23 to cylinder I, when the parts are in the normal positionindicated in Fig. 7, but, when turned it closes all passage throughconduit 31, and opens 36, and through 36 the interior of cylinder I, tothe atmosphere. This disables the clutch-operating power mechanism andleaves the clutch free for operation by the drivers foot in the usualmanner, as though our invention had not been applied to the car. This isthe main purpose of all the cut-out valves 24, 25 and 54. Some form ofcut-out of the character above described is required by law on everyfree-wheeling attachment in many states. In this valve no air port isshown for venting the portion of conduit 31 that extends to the valvecasing 1 as it really is not necessary to vent the valve. When valve 8has been cut off from connection with both intake manifold G andcylinder I, it can reciprocate freely with the dead air trapped in itscasing I.

The purpose of the short lengths of rubber hose l6, 46, shown in Figs. 1and 6 is to permit the cylinder l to swing slightly on its pivotmounting at 45, as is rendered necessary by the angularity of clutchpedal lever 4.

Mounting the power cylinder I on a swinging pivot 45, simplifies thepiston rod connections and also makes it easy to install the apparatuson any make of car by merely providing a special bracket 43 that can beattached to the most convenient adjacent portion of the chassis orsteering post, or motor base of the car.

Obviously any mechanism for automatically disengaging and engaging aclutch which is used for transmitting power from an internal combustionmotor of the four-cycle type such as is generally used on motor carsshould include means for producing a gradual, as distinguished from asudden, engagement between the members of the friction clutch usuallyemployed for connecting the freely revolving motor to the running gearof the car, which may be at rest or moving at a speed differing fromthat of the motor. This is necessary because such type of motor will notstart under load and the clutch has to be engaged after the motor hasbeen started, so that any sudden, and/or quickly completed clutchengagement would necessarily be accompanied by unpleasant and injuriousshocks resulting from sudden acceleration of the car, or a suddenchecking of the motor speed, or both.

In the standard make of motor cars the clutchcontrolling mechanismalready installed is normally biased, as by the spring 5 here shown, toclose the clutch. Consequently any power-operated mechanism foractuating the clutch is required to exert power only while opening theclutch, and then, after the power application is ended, the biased,spring-operated clutch-control mechanism will cause a clutch closuremodified as to rapidity by the drag of the dead servomotor, which isconnected to it.

Also, while a predetermined degree of decrease of speed of approach bythe movable element of the clutch toward its cooperating, axiallynonmovable, element during such clutch closing movement can be securedby the use of automatic mechanism, combined with the mainclutch-actuating apparatus or servo-motor such as here shown, it isalways desirable that such speed of engagement should be at least partlyunder manual control by the driver, as hereinbefore explained, since hecan sense the particular conditions then existing and consequently moreaccurately graduate the rate of clutch engagement needed to avoid shockand grabbing on the one hand, or slipping and burning of the clutch onthe other hand, and therefore can more successfully accomplish startingof the car and gear shifting than can any purely automatic apparatus.Also, the operator can sense any incipient shock developing as suchautomatic device is producing the initial clutch engagement, andthereupon immediately modify the same in a manner necessary to avoidfurther aggravation of such incipient jerking, clutch "grabbingphenomena.

If the power unit, or servo-motor, employed for actuating the clutchlever is a pneumatic motor, the type we have here shown and described asembodying one form of our present invention, such slowing down of theclutch-engaging operation involves control of the rate of inflow of airto the vacuum chamber of such motor, in this case the left-hand end ofcylinder i, or control of the outflow of air from an aircushion space,in this case the right hand end of such cylinder if the latter is madesubstantially air-tight as shown in Fig. 6.

This control of inflow and/or outflow is best effected by a valvecapable of accurately graduated adjustments of opening and closing ofthe air passages to and from the pneumatic motor. This adjustment may besecured by the use of a tapered valve portion such as the parts marked26, or 20a of the valve apparatus shown in Figs. 1, 2 and 6, butobviously other forms of valve or valve apparatus could be designed toproduce this effect. All that is needed is some kind of a valve undercontrol by the operator and acting to bleed the air out of anair-cushioning chamber which slows the clutch-engaging movement at anaccurately graduated rate, as does the tapered valve extension 20a inFig. 6, or to similarly bleed the air into a vacuum chamber, such as theleft-hand end of cylinder l, any remaining slight vacuum in which slowsthe clutch-engaging movement. Such graduated admission of air iscontrolled by the tapered valve extension 20 in Figs. 1 and 6.

It is always important, however, that the main valve apparatus, or thefunctioning of that portion of the valve apparatus which alternatelyconnects such pneumatic motor with the intakemanifold and theatmosphere, should completely close the manifold connection before theair inlet to the interior of the pneumatic motor is opened, and thatcontrol of any bleed action from the compression space in a servo-motorhaving a cylinder closed at both ends should be effected by extraneousmeans, since otherwise there will be either a momentary sucking of anexcess of air into the intake-manifold while the motor is still idling,which will render the mixture momentarily so lean that the motor of thecar will stall, or some other interference with efllcient operation ofthe apparatus. It is also important that the connection from acceleratorI2 to the throttle should include a lost-motion device, as beforeexplained, so that the accelerator will sequentially operate the vacuumcontrol valve and the throttle valve.

All these above described conditions and requirements are fully met inthe piston type of valves and valve apparatus hereinbefore described andshown in the drawings, in that each such valve piston has its fullbodied section long enough to produce the proper amount of lap withrespect to its cooperating valve port. Also the controlling meansafforded by the tapered portion 20a. of the valve piston shown in Fig. 6for controlling the escape of air from the compression end of cylinder Iis relatively remote from the suction-controlling valve piston 2|, 20and extraneous of the latter. These requirements should also be met inany equivalent valve apparatus-which may be substituted for thepreferred forms we have here shown in detail.

Other forms of pneumatic motors, or pneumatic servmmotors, might besubstituted for the cylindei piston type thereof which We have hereinshown, so long as such modifications come within the scope of ourinvention as defined in the appended claims.

Various changes could be made in the details of the constructions hereshown without departing from the underlying principles of the invention.Thus the parts could be reversed so as to operate by fluid pressureabove atmosphere derived from the exhaust manifold, instead of by thesub-atmospheric pressures derived from the intake manifold.

Also, while in the modification shown in Fig. 6 the conduit 5!, 3i,connecting that end of the servomotor cylinder 1 through which itspiston rod 3 protrudes with the intake manifold 6 and the valve means I,8, controlling said conduit, lie wholly outside of said cylinder,equivalent elements of the combination might be differently located, solong as the valve means comprise an element subject to manual adjustmentto control the flow of air from said cylinder end; whereby clutchclosing movements of piston 2a toward that end may be correspondinglycontrolled.

Having now fully described our invention what we claim is:

1. A vacuum power clutch mechanism having, in combination, a cylinderpivotally connected to the frame of the motor vehicle, piston in saidcylinder, a piston rod connected to said piston, a clutch pedal, meansfor connecting said piston rod to said clutch-pedal, said piston rodworking through a head in said cylinder, said head having meanscooperating with said piston rod to prevent air from leaking into or outof said cylinder, a valve casing having ports connected by passagewaysto said cylinder, a valve in said valve casing having part of itsperiphery in the form of a full bodied section and part of its peripherytapered, an intake-manifold connected by a passageway to said valvecasing, a second pedal pivotally connected to said valve, a carburetor,having a throttle valve, said carburetor throttle valve being alsooperatively connected to said second pedal and means for allowing saidfirst mentioned valve to be moved before said carburetor throttle valveis moved from the idling position.

2. In a pneumatic apparatus for actuating the clutch lever of a motorcar, the combination, with such clutch lever, of a cylinder having asubstantially air-tight closed end, a piston in said cylinder having apiston rod extending through said cylinder end and connected to saidlever, a conduit connected to the interior of the closed end of saidcylinder, and a valve apparatus controlling passage through said conduitcomprising a valve casing having a port to which such conduit isconnected anda valve piston having a sliding fit in said casing and alsohaving a relatively considerable portion of its length of a slightlytapering cross section adapted to cooperate with said port during aportion of its travel; whereby the flow of air from said closed end ofthe cylinder may be regulated by adjustment of such valve piston withreference to said port.

3. A pneumatically operable mechanism for controlling the clutch-leverof a motor car comprising, in combination, a cylinder having a pistontherein with a piston rod extending through, and having a substantiallyairtight bearing in, one head of said, cylinder and adapted to beconnected to a clutch lever, a tubular valve casing having a connectionto the intake manifold, separate conduits connecting either end of saidcylinder to separate ports in said valve casing, and a valve membermovable endwise in said casing and adapted by its motion alone toopcnsaid ports to their full widths or to close them, thereby opening,closing or partially restricting communication from said manifold tothat end of the cylinder opposite that through which said piston rodextends, and also the air inlet to and outlet from the other end of saidcylinder; whereby any vacuum existing in said intake manifold maybeutilized to move piston in one direction and its movement in the otherdirection may be controlled by graduating the degree of port opening forthe conduit connected to said last mentioned cylinder end substantiallyas described.

4. An apparatus such as defined in claim 3, combined with a throttlecontrolling member also operatively connected to said valve member so asto open the said manifold connection after the throttle has been closedand to close the manifold connection before the throttle is opened.

5. A pneumatically operable mechanism for controlling the clutch of amotor car comprising, in combination, a cylinder having a piston rodextending through, and having a substantially air-tight bearing in, onehead of said cylinder and adapted to be connected to a clutch lever, avalve casing having a connection to the intake manifold of the motorfrom a point approximately midway of the length of said casing, separateconduits connecting either end of said cylinder with separate ports insaid valve casing which are located on either side of said manifoldconnection and a double piston valve each head of which has a part ofits length in the form of a full bodied section and another parttapering, said valve being adapted to slide in said casing and therebyopen communication from said manifold connection to either one of saidconduits, said valve casing having an opening to the atmosphere ateither end.

6. A combination such as defined in claim 5 in which one of said taperedvalve sections extends toward the said manifold connection, while theother extends toward the nearest casing opening to the atmosphere.

7. A combination such as defined in claim 5 in which each said fullbodied valve section has a length at least as great as the width of itscooperating port; whereby said valve member is capable of simultaneouslylapping both said conduit ports and said first mentioned piston maythereby be held in any position which it may then have reached in itstravel in said cylinder.

8. In a pneumatic apparatus for actuating the clutch. lever of a motorcar having an internal combustion motor of the compression type and amanually operable accelerator for controlling the speed of such motor,the combination, with said clutch lever, of a servo-motor comprising acylinder having substantially air-tight closed ends one of which isconnected to the intake manifold of said car motor, a piston in saidcylinder having a piston rod extending through the other of saidcylinder ends and connected with'said lever, a conduit connected to theinterior of the last mentioned end of said cylinder, and a valveapparatus controlling passage through said conduit, said valve apparatusbeing operated by a connection to said accelerator; whereby the flow ofair from said end of the cylinder through said conduit may be regulatedby the adjustment of said accelerator.

9. A vacuum-power clutch-actuating mechanism having, in combination, acylinder connected to the frame of a motor vehicle, a piston in saidcylinder, a piston rod connected to said piston, a movableclutch-actuating member, means for connecting said piston rod to saidmember, an intake manifold, a valve apparatus for controlling themovement of said piston comprising a valve casing having ports, one ofwhich is connected to said cylinder and another to said intake manifold,together with an opening to the atmosphere, and a valve in said casingadapted either to connect said ports one with the other, or to close theport connected to the intake manifold before connecting said other portwith the atmosphere, a second movable member operatively connected tosaid valve, and a carburetor having a throttle valve also operativelyconnected to said second movable member, said valve apparatus havingmeans adapted to minutely graduate the rate of flow of air set in motionby movements of said piston.

10. A combination such as defined in claim 9 in which said valveoperating connection permits air to be admitted to said cylinder tocause a clutch closing movement of said clutch-actuating member beforethe opening of said throttle is begun.

11. In an automotive vehicle having a clutchoperating mechanism normallybiased to close the clutch, the combination of a vacuum-operatedservo-motor having a cylinder closed at both ends, said servo-motorbeing operably connected to said mechanism, and a manually operablevalve apparatus for producing alternately an eduction of air from, andadmission of air to, the suction end of said cylinder to initiate theclutch disengaging and engaging operations of said mechanism, said valveapparatus also com prising an element for accurately graduating theoutflow of air from the other, non-suction end of said motor cylinderand thereby similarly regulating the clutch-engaging operations of saidmechanism.

12. An apparatus such as defined in claim 11 combined with aspeed-controlling device for said vehicle and an operative connection bymeans of which said device also controls said valve apparatus.

13. In an automotive vehicle equipped with a movable clutch-actuatingmember, an internal combustion motor of the four-cycle type, av

. throttle valve therefor, a device controlling said throttle valve, avacuum motor having a vacuum connection to the intake manifold of saidfirst mentioned motor and an operative connection to saidclutch-actuating member, said vacuum connection having a valve forclosing it and thereafter admitting air to said vacuum motor to permitsaid member to effect a clutch-closing movement, the combination, withsaid above described apparatus of means extraneous of said lastmentioned valve and controlled by said throttle-operating device formore accurately graduating such clutch-engaging movement of said member.

14. A combination such as defined in claim 13 in which said meanscomprises a bleed valve operable by said throttle-controlling device.

15. A combination such as defined in claim 13 in which saidthrottle-controlling device sequentially actuates saidvacuum-controlling valve and said throttle valve.

16. In a clutch control mechanism having a clutch controlling member, adouble-ended fluid motor having a movable element operatively connectedwith said member, a control valve for said motor and connectionsinterconnecting each end of said motor with said valve, said valvecomprising a one-piece casing and a one-piece reciprocable valve membermounted for sliding movement within said casing, said latter member,being provided with a tapered portion for variably determining the modeof efliux of air from said motor depending upon the position of saidvalve member and thereby accurately graduating the clutch-engagingmovement of said clutch controlling member.

17. In a pneumatic apparatus for actuating the clutch controlling memberof a motor car, which said apparatus is connected to the intake manifoldof such car, a valve apparatus for controlling said connection and foradmitting air to said pneumatic apparatus only after said manifoldconnection-has been temporarily closed, which said valve apparatuscomprises, in combination, means for quickly opening said maniioldconnection and air bleed means for accurately graduating the clutchclosing movement of said member, said penumatic apparatus including asubstantially closed air chamber in which air is compressed during thelatter portion of the clutch closing movement of said clutch controllingmember, and in which said air bleed means controls the outflow of airfrom said chamber.

18. In a pneumatic apparatus for actuating the clutch controlling memberof a motor car, which said apparatus is connected to the intake manifoldof such car, a valve apparatus for controlling said connection and foradmitting air to said pneumatic apparatus only after said manifoldconnection has been temporarily closed, which said valve apparatuscomprises, in combination, means for quickly opening said manifoldconnection and air bleed means for accurately graduating the clutchclosing movement of said member, said pneumatic apparatus including asubstantially closed air chamber in which air is compressed during thelatter portion of the clutch closing movement of said clutch controllingmember, and in which said air bleed means controls the outflow of airfrom said chamber, combined with an operative connection from said valveapparatus to the accelerator pedal of such car.

19. In an automotive vehicle having a clutch mechanism and a clutchreturn spring, a vacuum operated double-ended fluid motor operablyconnected to said mechanism, a manually operable valve for controllingthe eduction and admission of air to the one side of the motor toinitiate the disengaging and engaging operations of the clutchmechanism, and a second manually operable valve simultaneously operablewith the first valve for controlling the eduction of air from the otherside of the motor to control the operation of the clutch return springin regulating the clutch engaging operation of said clutch mechanism.

20. An automotive vehicle provided with an internal-combustion engine, athrottle for said engine, and a clutch mechanism, a double-endedpressure differential operated motor operably connected with the clutchmechanism, a valve unit for controlling the gaseous pressure within 15both ends of the motor, and common manually operable means for operatingboth the throttle and the valve unit to control both the clutchdisengaging and engaging operations of said mo tor and the operation ofthe internal-combustion engine.

21. An automotive vehicle provided with an internal-combustion engine, athrottle therefor, an accelerator. a clutch mechanism, and comprising incombination therewith a double-ended vacuum operated motor operablyconnected. with the clutch mechanism, valve means for controlling thegaseous pressure Within one end of said motor, and other valve means forcontrolling the gaseous pressure within the other end of the motor, bothof said valve means and said throttle being operated by saidaccelerator.

22. An automotive Vehicle provided with an internal-combustion engineand a clutch mechanism, a throttle for said engine, and an engineope-rated double-ended vacuum motor operably connected with theclutchmechanism, a valve unit for controlling the operation of themotor, said unit comprising a three-way valve associated with one end ofsaid motor and. a bleed valve associated with the other end of said mo-'sage of air between said cylinder and the intake manifold.

24. A combination such as defined in claim 9 in which said last namedmeans is adapted to minutely control the flow of external air to theinterior of said cylinder during at least a portion of the period of theclutch-closing movement of said clutch-actuating member.

25. In a clutch actuating apparatus for motor cars the combination, witha reciprocable memher for opening and closing the clutch and a gasengine having an intake manifold in which varying degrees of vacuumexist according to running conditions, of a vacuum actuated servomotorcomprising a cylinder having closure heads at both ends and a connectionfrom one end to said manifold, a piston reciprocable in said cylinderhaving a rod extending through the head at the other cylinder end andconnected to said re ciprocable member, and valve means for controllingany flow of air from said last mentioned cylinder end to said manifoldhaving an adjust-- able element participating in said flow controltogether with a manually controllable device operatively connected tosaid adjustable element which is separate from, and devoid of operativeconnections with, the hereinbefore mentioned reciprocable member foropening and closing the clutch; whereby movements of said piston towardsaid last mentioned cylinder. end may be correspondingly controlled.

26. A combination such as defined in claim in which said manuallycontrollable device is provided with connections enabling it to alsoserve as an accelerator for controlling the speed of said gas engine.

27. A combination such as defined in claim 25 in which said adjustablevalve element also participates in the control of any inflow of air tosaid last mentioned cylinder end.

HENRY JOHN DE NEVILLE MCCOLLUM. JAMES HARRY KEIGHLEY MCCOLLUM.

